The present invention relates to an envelope generator for use in the keyer circuitry of an electronic organ for imparting predetermined envelope configuration to the sounds produced by the organ upon depression of a key.
Electronic organs are, of course, well known and have as a general objective the provision of music which, in many cases, simulates the sound of known instruments. Among the instruments, the sound of which it is desired substantially to duplicate in an electronic organ, are percussion type instruments, such as piano, harpsichord, banjo, glockenspiel, xylophone and the like. Such organs usually use voltage sensitive keyers to control the passage of tone signals and control the voltage supply to the keyers to impart a desired envelope to the tones controlled by the keyers. In the case of percussion instruments, a fast attack and controlled decay are desired for a sounded tone.
Heretofore, it has not been a simple matter to arrive at a suitable control system for controlling the actuating voltage supplied to a keyer to obtain realistic simulations of instruments referred to above, and to obtain flexibility of control.
The present invention has as a particular object the provision of a circuit for developing keyer control voltages which will effect control of the keyer in such a manner as to simulate the sounds of the nature referred to and in a relatively simple and inexpensive manner.
Another object is the provision of a circuitry for supplying keyer voltage to a keyer, or keyers, in electronic organs in which the voltage supplied to the keyer is selectively operable to control the voltage supply to the keyer so as to produce percussion sounds which will die away at a determined note and go off, or which can control the keyer voltage so as to maintain a keyed note as long as the respective key is depressed.